Carpenters, craftsman, and the all around handy man need a tool that is capable of placing screws into material accurately, and reliably. Utilizing a powered drill is the most viable option because the drill provides mechanical advantages that far surpass the conventional screw driver. With the slight pull of the trigger a powered drill is capable of providing many foot pounds of torque that is capable of placing screws into various materials accurately and effectively.

+

Carpenters, craftsman, and the all around handy man need a tool that is capable of placing screws into material accurately, and reliably. Utilizing a powered drill is the most viable option because the drill provides mechanical advantages that far surpass the conventional screw driver. With the slight pull of the trigger a powered drill can provide many foot pounds of torque that are capable of placing screws into various materials accurately and effectively.

−

By carefully analyzing the Black and Decker DR202 it is clear to see why this drill has been a consumer favorite over the years. At first glance one may be attracted to the black and red color scheme that has became the standard for Black and Decker products. The outer covering is made of a sturdy plastic along with rubber grips for added comfort and control. Other features that help to separate the Black and Decker DR202 from other powered drills on the market are the level on the back of the drill as well as a keyless chuck. Taking a closer look under the outer casing a powerful 5 Amp motor is utilized to provide adequate power for the toughest jobs.

+

By carefully analyzing the Black and Decker DR202 it is clear to see why this drill has been a consumer favorite over the years. At first glance one may be attracted to the black and red color scheme that has became the standard for Black and Decker products. The outer covering is made of a sturdy plastic along with rubber grips for added comfort and control. Other features that help to separate the Black and Decker DR202 from other powered drills on the market is the level on the back of the drill as well as the key-less chuck. Taking a closer look under the outer casing a powerful 5 Amp motor is utilized to provide adequate power for the toughest jobs.

Granted, Black and Decker has created a drill that accurately and reliably drills screws into various materials there is still room for improvement. By disassembling and reviewing the manufacture processes, material type, and function of ease individual component of the DR202 our team was able to suggest some design changes. These design changes could be implemented to keep the Black and Decker DR202 drill on the top of the competitive marketplace.

Granted, Black and Decker has created a drill that accurately and reliably drills screws into various materials there is still room for improvement. By disassembling and reviewing the manufacture processes, material type, and function of ease individual component of the DR202 our team was able to suggest some design changes. These design changes could be implemented to keep the Black and Decker DR202 drill on the top of the competitive marketplace.

−

==Introduction==

+

==Before Disassembly Section==

+

+

===Introduction:===

The objective of this project was to examine the Black and Decker DR202 powered drill. By disassembling, reassembling, and reviewing the inner workings of the drill our group was successfully able to grasp how the DR202 was manufactured and how to improve upon the design of the DR202.

The objective of this project was to examine the Black and Decker DR202 powered drill. By disassembling, reassembling, and reviewing the inner workings of the drill our group was successfully able to grasp how the DR202 was manufactured and how to improve upon the design of the DR202.

+

Our group was a collaboration of five dedicated individuals whose contributions are noted below

Our group was a collaboration of five dedicated individuals whose contributions are noted below

−

Andrew Klahr (group leader)-List contributions here<br>

−

Anne-Marsha Joseph- List contributions here<br>

−

Katie Weber- List contributions here<br>

−

Anthony Beeman - List contributions here<br>

−

Yan Liang-List contributions here<br>

−

==Before Disassembly Section==

+

Andrew Klahr (group leader)- Presentation, Parts Analysis<BR>

+

Anne-Marsha Joseph- Presentation, Disassembly<BR>

+

Katie Weber- Disassembly, Part Analysis<BR>

+

Anthony Beeman - WIKI Page, Reassembly<BR>

+

Yan Liang- CAD Drawings, Reassembly<BR>

−

<b>Purpose:</b><BR>

+

===Purpose:===

The purpose of the Black and Decker DR202 was to fasten and remove screws into materials such as drywall, sheet rock, and wood. The DR202 is able to accurately and reliably place screws into various materials with the aid of the level that is provided on the drill. Drill bits can be removed by utilizing the keyless chuck. The DR202 chuck is capable of holding drill bits that fall within the range of 1–10 mm. Each bit can perform specific functions when utilized with the DR202. For example some bits are used to create holes in materials while other bits can be utilized to drive screws into materials. The DR202 is powered by 120 volts of alternating current and has the capability of rotating clock wise as well as counter clockwise.

The purpose of the Black and Decker DR202 was to fasten and remove screws into materials such as drywall, sheet rock, and wood. The DR202 is able to accurately and reliably place screws into various materials with the aid of the level that is provided on the drill. Drill bits can be removed by utilizing the keyless chuck. The DR202 chuck is capable of holding drill bits that fall within the range of 1–10 mm. Each bit can perform specific functions when utilized with the DR202. For example some bits are used to create holes in materials while other bits can be utilized to drive screws into materials. The DR202 is powered by 120 volts of alternating current and has the capability of rotating clock wise as well as counter clockwise.

−

<b>Components:</b><BR>

+

===Components:===

Our group estimated the DR202 powered drill would consist of 30 parts. Some of these parts are listed below:<BR>

Our group estimated the DR202 powered drill would consist of 30 parts. Some of these parts are listed below:<BR>

1 Directional Switch<BR>

1 Directional Switch<BR>

Line 35:

Line 37:

9 Bit<BR>

9 Bit<BR>

−

<b>Materials:</b><BR>

+

===Materials:===

Prior to disassembling the Black and Decker DR202 our group believed the power drill consisted of 4 types of materials.<BR>

Prior to disassembling the Black and Decker DR202 our group believed the power drill consisted of 4 types of materials.<BR>

1 Copper<BR>

1 Copper<BR>

Line 43:

Line 45:

==Disassembly Procedure==

==Disassembly Procedure==

−

+

<BR>

+

<BR>

{| border="3" cellspacing="0" cellpadding="3" align="center"

{| border="3" cellspacing="0" cellpadding="3" align="center"

! width="50"|Step #

! width="50"|Step #

Line 52:

Line 55:

|-

|-

| align="center" |1

| align="center" |1

−

| align="center" |Type Description Here

+

| align="center" |Took out the nine screws.

−

| align="center" |Type Tools Used Here

+

| align="center" |Flathead Screwdriver

−

| align="center" |Type Level of Difficulty Here

+

| align="center" |Moderately Difficult

|-

|-

|-

|-

| align="center" |2

| align="center" |2

−

| align="center" |Type Description Here

+

| align="center" |Pried the plastic bit holder out.

−

| align="center" |Type Tools Used Here

+

| align="center" |Flathead Screwdriver

−

| align="center" |Type Level of Difficulty Here

+

| align="center" |Easy

−

|-

+

|-

|-

| align="center" |3

| align="center" |3

−

| align="center" |Type Description Here

+

| align="center" |Separated the right side of the casing from the left side of the casing. As doing so the directional lever fell out.

−

| align="center" |Type Tools Used Here

+

| align="center" |Hands

−

| align="center" |Type Level of Difficulty Here

+

| align="center" |Easy

|-

|-

|-

|-

| align="center" |4

| align="center" |4

−

| align="center" |Type Description Here

+

| align="center" |Placing the left side of the casing down, we pulled the motor and attachments out of the casing.

−

| align="center" |Type Tools Used Here

+

| align="center" |Hands

−

| align="center" |Type Level of Difficulty Here

+

| align="center" |Easy

|-

|-

|-

|-

| align="center" |5

| align="center" |5

−

| align="center" |Type Description Here

+

| align="center" |Removed two more screws which were holding a metal plate down, which was holding the wires leading to the cord in place.

−

| align="center" |Type Tools Used Here

+

| align="center" |Flathead Screwdriver

−

| align="center" |Type Level of Difficulty Here

+

| align="center" |Moderately Difficult

|-

|-

|-

|-

| align="center" |6

| align="center" |6

−

| align="center" |Type Description Here

+

| align="center" |Pulled out the chuck and attached gears.

−

| align="center" |Type Tools Used Here

+

| align="center" |Hands

−

| align="center" |Type Level of Difficulty Here

+

| align="center" |Easy

|-

|-

|-

|-

| align="center" |7

| align="center" |7

−

| align="center" |Type Description Here

+

| align="center" |Separated the gear system from the motor.

−

| align="center" |Type Tools Used Here

+

| align="center" |Hands

−

| align="center" |Type Level of Difficulty Here

+

| align="center" |Easy

|-

|-

|-

|-

| align="center" |8

| align="center" |8

−

| align="center" |Type Description Here

+

| align="center" |Separated the individual gears that made up the gear system.

| align="center" |Connect the individual gears that made up the gear system.

−

| align="center" |Type Tools Used Here

+

| align="center" |Hands

−

| align="center" |Type Level of Difficulty Here

+

| align="center" |Easy

|-

|-

|-

|-

| align="center" |2

| align="center" |2

−

| align="center" |Type Description Here

+

| align="center" |Place motor into the left cover.

−

| align="center" |Type Tools Used Here

+

| align="center" |Hands

−

| align="center" |Type Level of Difficulty Here

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| align="center" |Difficult

|-

|-

|-

|-

| align="center" |3

| align="center" |3

−

| align="center" |Type Description Here

+

| align="center" |Place the gear system into the left cover.

−

| align="center" |Type Tools Used Here

+

| align="center" |Hands

−

| align="center" |Type Level of Difficulty Here

+

| align="center" |Easy

|-

|-

|-

|-

| align="center" |4

| align="center" |4

−

| align="center" |Type Description Here

+

| align="center" |Place the two screws into the metal plate and used them to secure the wires within the left cover.

−

| align="center" |Type Tools Used Here

+

| align="center" |Phillips Screwdriver

−

| align="center" |Type Level of Difficulty Here

+

| align="center" |Easy

|-

|-

|-

|-

| align="center" |5

| align="center" |5

−

| align="center" |Type Description Here

+

| align="center" |Place inverter and trigger back into left cover.

−

| align="center" |Type Tools Used Here

+

| align="center" |Hands

−

| align="center" |Type Level of Difficulty Here

+

| align="center" |Easy

|-

|-

|-

|-

| align="center" |6

| align="center" |6

−

| align="center" |Type Description Here

+

| align="center" |Connect the directional lever to the motor.

−

| align="center" |Type Tools Used Here

+

| align="center" |Hands

−

| align="center" |Type Level of Difficulty Here

+

| align="center" |Moderate

|-

|-

|-

|-

| align="center" |7

| align="center" |7

−

| align="center" |Type Description Here

+

| align="center" |Place right cover over the drill.

−

| align="center" |Type Tools Used Here

+

| align="center" |Hands

−

| align="center" |Type Level of Difficulty Here

+

| align="center" |Easy

|-

|-

|-

|-

| align="center" |8

| align="center" |8

−

| align="center" |Type Description Here

+

| align="center" |Place 9 screws into Left cover and connected left and right cover.

−

| align="center" |Type Tools Used Here

+

| align="center" |Phillips Screwdriver

−

| align="center" |Type Level of Difficulty Here

+

| align="center" |Easy

|-

|-

−

−

|}

|}

+

<br>

+

<br>

==After Assembly==

==After Assembly==

+

<br>

+

===How It Works===

+

After disassembling the product, the function of each part, as well as how the overall

+

product operated, was accessed.<BR>

+

+

This drill has a universal motor. It runs off of an alternating current (AC) power supply,

+

which comes from an outlet. The motor contains a rotor that has copper wire wrapped around it. The copper wire is used to create a magnetic field. As the AC power is supplied to the rotor, it creates a magnet. The rotor is also surrounded by another magnet with the north pole of the rotor’s magnet attached to the south of the additional magnet. According to the magnetic theory, the opposite poles of each magnet attract each other, while the like poles repel each other. With this relationship, the two magnets begin to repel each other, which cause the rotor to turn. The motor is also made up of small pieces of metal called “brushes”. These brushes rub against a disk that’s attached to the shaft. When the AC power is supplied to the motor and the rotor turns due to the magnetic forces, the brushes transfer electricity to the shaft, which causes it to turn. As the shaft rotates, it causes the gears to turn as well, which then makes the chuck rotate. As the user applies force to the drill and the chuck rotates, the screw enters the targeted material. There is a cooling fan attached to the shaft that helps keep the motor from overheating. It also rotates as the shaft rotates. After reassembling the drill, it ran the same as it did before the disassembly.<BR>

−

*Does it still work?

+

<BR>

−

*Conclusion remarks

+

−

==References==

+

===Product Analysis===

−

[http://www.apastyle.org/ APA Style]

+

<BR>

−

You must use this format (It's easier than MLA, so don't worry).

+

−

===Guide to Writing Wiki Code===

+

----

−

The beauty about Wiki is that if you don't know the code, you can steal it from someone's page that does. Feel free to click the "edit" links or tabs to view the code for sections or the pages respectively. Be weary about wrecking havoc on another's page. Each page can be rollbacked to a previous verison and your username is linked to all changes. Although you might think it's cool to go through and insert "MIKE RULES" throughout the page, I'm sure Dr. Lewis would not be pleased.

+

<b>Note To The Reader:</b> <i>The purpose of this product analysis is to walk you through the engineering thought process while solving the analytical problem noted below.</i>

The calculations to the gear system would require extensive understanding of many dynamics concepts and will be explained in the discussion<BR>

+

<BR>

+

<b>Solutions Check</b><BR>

+

One would verify numerical values as well as unit consistency.

+

<BR>

+

<BR>

+

<b>Discussion</b><BR>

+

By calculating the angular moment of inertia and angular acceleration "w" of each gear one could then sum the torques of gear system in a piecewise manner. The sum of the torques would be the final output torque of the systems. Torques rotating counter clock wise would be considered positive while torques rotating clock wise would be considered negative. By varying the gear ratios and the initial torque of the motor one could vary the output torque of the system. The assumptions make sense when calculating the max torque of the system. One benefit of this system is that it can be adapted to calculate the torque as a function of time; the motor torque varies. In order to calculate the torque at a given time the motors torque would have to be illustrated by a function M(t). This function would be non-linear in nature due to the exponential increase in the motor torque over time; Until the max moment is reached. By carefully analyzing and optimizing the system above a new max torque could be created.

+

<BR>

+

<BR>

+

===Ergonomic Analysis===

+

<BR>

+

By testing the user interaction with the product, concepts such as center of balance and user comfort can be tested. With the use of a working prototype the analysis can take place. Issues such as grip comfort and handling of the drill can be addressed.

+

<BR>

−

This is a brace "{" "}"

+

===Disassembly/Assembly Discussion===

−

+

The disassembly and assembly procedures were the reverse of each other. The disassembly process was very easy and only required the use of a flat head screw driver and our hand. Once we had opened the casing the process was very easy because the housing of the drill was the only component holding the parts in place besides 2 screws on the inside. The assembly process was more time consuming due to the fact that each part had to be put back together in working order, which with the aligning the gear system, the process was somewhat tedious. The same tools were used in both the disassembly and reassembly process. The drill is back together in working order, same as when we received it prior to disassembly.

−

To create a new page/link within Wiki:

+

===Recommended Design Changes===

−

*Double brackets, page name, double brackets

+

The drill has a few small weakness in its design. With the following recommended design changes, the product will be more appealing to the user:

−

*Typing in a new page name will automatically create a page, which when clicked, you can then edit.

+

−

*Whatever name you first type in is the name of the page. You can't change page names, only create new pages. Think before you create a new page.

+

1. Directional Changer - The directional changer was very large and awkward to use. With a simple button or small sliding mechanism, the directional changer would be much easier to use.

−

*Don't worry about slashes or anything, all pages are located in the same directory. If I wanted to create a page called "MAE 277 Template" the code would be ''[[''MAE 277 Template'']]'' Note: Brackets are italicized to prevent creating a new page.

+

+

2. Screws - Black and Decker uses two different types of screws that both contain hexagonal screw heads. With the use of phillips or flat-head screws, repairs and disassembly would be much easier. Also, eliminating the the different screws and replacing them with a uniform design would be more cost effective for Black and Decker.

−

Your table of contents is created automatically.

+

3. Cord - A battery operating drill is a more practical design choice. The cord seems to just get in the way and a battery operated drill does not limit the use of where the drill can be used.

−

*1,2,3,4 are level 2 sections

+

−

*1.1, 1.2, 1.3 are level 3 headers

+

+

4. Drill bit - The bit that is included with the drill is a very basic design. The use of a magnetic bit, or a bit with a sleeve over it would be more user friendly.

"br" in "<>" will break lines. They can also be used to separate section headers.

+

−

+

−

<br><br>

+

−

Finally, use the <i>"Show Preview"</i> button on the bottom of the page to see how it looks before saving. It will allow you to catch and edit your errors without having to edit the page again. <b>Just don't forget to save it when you're really done.</b>

+

−

+

−

===This is an example table===

+

−

+

−

{| border="1" align="center"

+

−

|+ '''This is the table title'''

+

−

! width="75"|This is Column Header 1

+

−

! width="400"|This is Column Header 2

+

−

! width="200"|This is Column Header 3

+

−

|-

+

−

! This starts Row 1

+

−

| align="center"|Width values (pixels) in header are used to designate the width of the column for the entire table. Text will wrap but it helps to control the layout. Height of the row is determined by the row's largest content

+

−

| A return and single vertical lines separate columns in rows. A double vertical line is necessary if you don't break up the text for cells.

|align="center"|Some html tags can be used, but not many. Notice the align equals center tag at the beginning of the row. It centers the text in the first two columns, but doesn't work for the third column. I don't know why. Adding the tag again to the beginning of the cell in question will center the text.

+

−

|-

+

−

! This starts Row 3

+

−

|align="center"|Image tags are in this format:

+

−

<br>Double brackets "[["

+

−

<br>Image name

+

−

<br>| = Vertical Line

+

−

<br><br>The following order is not important, as long as each is separated by a vertical line:

+

−

*Horizontal position (left, center, right)

+

−

*Thumb (to create clickable thumbnail that links to fullsize image), don't include to make a fullsize

+

−

*Size denoted in pixels (if desired)

+

−

*You can add a caption if there is a thumbnail

+

−

<br>Then close with double brackets "]]"

+

−

<br><br>Broken links show up in red.

+

−

<br>[[Image:This is a broken link|center|thumb|150px]]

+

−

<br>[http://gicl.cs.drexel.edu/wiki/Special:Imagelist Here's where you can view any uploaded files]

<br>This is a resized image, not a thumbnail, but notice you can still click on it to get the full size.

+

−

|-

+

−

! This starts Row 4

+

−

|align="center"|Notice the repeating code for every row? It's important. A vertical line and a dash indicate the start of a new row. An exclamation point indicates the first column. You can put the entire row onto a single line, but it's easier to read if you break it up. Again, wiki usually ignores new paragraphs.

+

−

|Make sure to end the table correctly (vertical line and closed brace). Not doing so might still display the table, but nothing that comes afterwards.

Executive Summary

Black and Decker DR202

Carpenters, craftsman, and the all around handy man need a tool that is capable of placing screws into material accurately, and reliably. Utilizing a powered drill is the most viable option because the drill provides mechanical advantages that far surpass the conventional screw driver. With the slight pull of the trigger a powered drill can provide many foot pounds of torque that are capable of placing screws into various materials accurately and effectively.

By carefully analyzing the Black and Decker DR202 it is clear to see why this drill has been a consumer favorite over the years. At first glance one may be attracted to the black and red color scheme that has became the standard for Black and Decker products. The outer covering is made of a sturdy plastic along with rubber grips for added comfort and control. Other features that help to separate the Black and Decker DR202 from other powered drills on the market is the level on the back of the drill as well as the key-less chuck. Taking a closer look under the outer casing a powerful 5 Amp motor is utilized to provide adequate power for the toughest jobs.

Granted, Black and Decker has created a drill that accurately and reliably drills screws into various materials there is still room for improvement. By disassembling and reviewing the manufacture processes, material type, and function of ease individual component of the DR202 our team was able to suggest some design changes. These design changes could be implemented to keep the Black and Decker DR202 drill on the top of the competitive marketplace.

Before Disassembly Section

Introduction:

The objective of this project was to examine the Black and Decker DR202 powered drill. By disassembling, reassembling, and reviewing the inner workings of the drill our group was successfully able to grasp how the DR202 was manufactured and how to improve upon the design of the DR202.

Our group was a collaboration of five dedicated individuals whose contributions are noted below

Purpose:

The purpose of the Black and Decker DR202 was to fasten and remove screws into materials such as drywall, sheet rock, and wood. The DR202 is able to accurately and reliably place screws into various materials with the aid of the level that is provided on the drill. Drill bits can be removed by utilizing the keyless chuck. The DR202 chuck is capable of holding drill bits that fall within the range of 1–10 mm. Each bit can perform specific functions when utilized with the DR202. For example some bits are used to create holes in materials while other bits can be utilized to drive screws into materials. The DR202 is powered by 120 volts of alternating current and has the capability of rotating clock wise as well as counter clockwise.

Disassembly Procedure

Separated the right side of the casing from the left side of the casing. As doing so the directional lever fell out.

Hands

Easy

4

Placing the left side of the casing down, we pulled the motor and attachments out of the casing.

Hands

Easy

5

Removed two more screws which were holding a metal plate down, which was holding the wires leading to the cord in place.

Flathead Screwdriver

Moderately Difficult

6

Pulled out the chuck and attached gears.

Hands

Easy

7

Separated the gear system from the motor.

Hands

Easy

8

Separated the individual gears that made up the gear system.

Hands

Easy

After Disassembly

Parts Table

Part Number

Part Name

Quanity

Materials

Manufacture Process

Purpose

Picture

1

outer casing (left)

1

PA6/G40 plastic and rubber

Injection Molded

Cover is made to hold the inner parts.

Left Outer Casing

2

outer casing (right)

1

PA6/G40 plastic and rubber

Injection Molded

Cover is made to hold the inner parts.

Right Outer Casing

3

3/4" Screws with #15 Torx heads

9

Steel

Extruded and Machined

Holds separate components together

3/4" Screws

4

1 7/8" Screws with #15 Torx heads

2

Steel

Extruded and Machined

Holds separate components together

1 7/8" Screws

5

Bit Holder

1

Plastic

Injection Molded

Holds one bit

Bit Holder

6

Bubble Level

1

Plastic

Extruded

Bubble level is used to ensure the user that the screw is being driven into the material at a right angle.

Bubble Level

7

Directional Lever

1

Plastic

Injection Molded

Allows the drill to spin clockwise and counter clockwise.

Directional Lever

8

Double sided bit

1

Steel

Extruded and Machined

Insertion of Phillips and flat head screws

Drill Bit

9

Power Cord

1

PlasticCopper

Extruded

Provide AC current to the power inverter

Power Cord

10

Inverter

1

PlasticCopperWoven glass

Injection moldingSilk screen printingPhotoengravingPCB milling

Converts current from AC to DC allowing the motor to utilize the provided current.

Inverter

11

Trigger

1

Plastic

Injection Molded

Utilized as switch to open and close the circuit.

Trigger

12

Internal Wiring

2

CopperPlastic (Insulation)

Extruded

Transport current from the inverter to the motor.

Wires

13

Motor

1

SteelPlasticCopper

Machined

Spins Shaft that rotates the gear system.

Motor

14

Cooling Fan

1

Plastic

Machined

Keeps motor from overheating.

Cooling Fan

15

Key Less Chuck

1

Plastic

Injection MoldingMetal Casting

Holds a bit that can be removed by the user.

Chuck

16

Gear System(Table Below)

1

Steel

Noted On Gear System Table

Through a series of gear reductions the gear system creates a torque.

Gear System

Gear System Table

Part Number

Part Name

Quanity

Materials

Manufacture Process

Purpose

Picture

17

Motor Shaft

1

Stainless Steel

Extruded

Connects to the motor to rotate the gear system.

Motor Shaft

18

Plate (a)

1

Stainless Steel

Metal Casting

Fits firmly onto the outer casing in order to secure the motor shaft.

Plate (a)

19

Plate (b)

1

Stainless Steel

Metal Casting

Fits firmly onto the outer casing in order to secure the motor shaft.

Plate (b)

20

Gear

1

Stainless Steel

Machined

Connects to the motor shaft to rotate the gear and pinion.

Gear

21

Gear and Pinion

1

Stainless Steel

Machined

Connects to the gear in order to create a torque.

Gear and Pinion

3D Computer Aided Design

Assembly Part 1

Assembly Part 2

Assembly Part 3

Final Assembly

Assembly

Step #

Description

Tool(s)

Level of Difficulty

1

Connect the individual gears that made up the gear system.

Hands

Easy

2

Place motor into the left cover.

Hands

Difficult

3

Place the gear system into the left cover.

Hands

Easy

4

Place the two screws into the metal plate and used them to secure the wires within the left cover.

Phillips Screwdriver

Easy

5

Place inverter and trigger back into left cover.

Hands

Easy

6

Connect the directional lever to the motor.

Hands

Moderate

7

Place right cover over the drill.

Hands

Easy

8

Place 9 screws into Left cover and connected left and right cover.

Phillips Screwdriver

Easy

After Assembly

How It Works

After disassembling the product, the function of each part, as well as how the overall
product operated, was accessed.

This drill has a universal motor. It runs off of an alternating current (AC) power supply,
which comes from an outlet. The motor contains a rotor that has copper wire wrapped around it. The copper wire is used to create a magnetic field. As the AC power is supplied to the rotor, it creates a magnet. The rotor is also surrounded by another magnet with the north pole of the rotor’s magnet attached to the south of the additional magnet. According to the magnetic theory, the opposite poles of each magnet attract each other, while the like poles repel each other. With this relationship, the two magnets begin to repel each other, which cause the rotor to turn. The motor is also made up of small pieces of metal called “brushes”. These brushes rub against a disk that’s attached to the shaft. When the AC power is supplied to the motor and the rotor turns due to the magnetic forces, the brushes transfer electricity to the shaft, which causes it to turn. As the shaft rotates, it causes the gears to turn as well, which then makes the chuck rotate. As the user applies force to the drill and the chuck rotates, the screw enters the targeted material. There is a cooling fan attached to the shaft that helps keep the motor from overheating. It also rotates as the shaft rotates. After reassembling the drill, it ran the same as it did before the disassembly.

Product Analysis

Note To The Reader:The purpose of this product analysis is to walk you through the engineering thought process while solving the analytical problem noted below.

Please Note: positive X is to the left, positive Y points up, and a positive moment is counter clockwise.

Assumptions:
Motor will provide an initial torque (Represented by "m" on the FBD)
Gears in the gear system are different sizes
Motor is capable of providing a torque that turns the gear
Gears don't slip while rotating
The motors torque doesn't vary with time
All surfaces are frictionless

Calculations
The calculations to the gear system would require extensive understanding of many dynamics concepts and will be explained in the discussion

Solutions Check
One would verify numerical values as well as unit consistency.

Discussion
By calculating the angular moment of inertia and angular acceleration "w" of each gear one could then sum the torques of gear system in a piecewise manner. The sum of the torques would be the final output torque of the systems. Torques rotating counter clock wise would be considered positive while torques rotating clock wise would be considered negative. By varying the gear ratios and the initial torque of the motor one could vary the output torque of the system. The assumptions make sense when calculating the max torque of the system. One benefit of this system is that it can be adapted to calculate the torque as a function of time; the motor torque varies. In order to calculate the torque at a given time the motors torque would have to be illustrated by a function M(t). This function would be non-linear in nature due to the exponential increase in the motor torque over time; Until the max moment is reached. By carefully analyzing and optimizing the system above a new max torque could be created.

Ergonomic Analysis

By testing the user interaction with the product, concepts such as center of balance and user comfort can be tested. With the use of a working prototype the analysis can take place. Issues such as grip comfort and handling of the drill can be addressed.

Disassembly/Assembly Discussion

The disassembly and assembly procedures were the reverse of each other. The disassembly process was very easy and only required the use of a flat head screw driver and our hand. Once we had opened the casing the process was very easy because the housing of the drill was the only component holding the parts in place besides 2 screws on the inside. The assembly process was more time consuming due to the fact that each part had to be put back together in working order, which with the aligning the gear system, the process was somewhat tedious. The same tools were used in both the disassembly and reassembly process. The drill is back together in working order, same as when we received it prior to disassembly.

Recommended Design Changes

The drill has a few small weakness in its design. With the following recommended design changes, the product will be more appealing to the user:

1. Directional Changer - The directional changer was very large and awkward to use. With a simple button or small sliding mechanism, the directional changer would be much easier to use.

2. Screws - Black and Decker uses two different types of screws that both contain hexagonal screw heads. With the use of phillips or flat-head screws, repairs and disassembly would be much easier. Also, eliminating the the different screws and replacing them with a uniform design would be more cost effective for Black and Decker.

3. Cord - A battery operating drill is a more practical design choice. The cord seems to just get in the way and a battery operated drill does not limit the use of where the drill can be used.

4. Drill bit - The bit that is included with the drill is a very basic design. The use of a magnetic bit, or a bit with a sleeve over it would be more user friendly.